A Millimeter-wave Bridge-Type MMIC Switch

A novel bridge-type switch is proposed employing a bridge circuit consisting of four switching devices and a balun. The isolation of conventional switches consisting of series and shunt type is limited by the switching device´s performance, namely, the ON resistance (Ron) and the OFF capacitance (Coff). A feature of the bridge-type switch is that its isolation characteristics do not depend on Ron and Coff of the switching devices, but instead on the accuracy of the balancing bridge circuit. The isolation for deviation of the bridge circuit elements and ON-state characteristics are calculated using a simple FET model. The bridge-type MMIC switch achieves less than 6 dB insertion loss and greater than 25 dB isolation in the broad frequency band up to 40 GHz.